Maritime passage,the Montreux Convention (1936) and the conflict between Russia and Ukraine

Introduction

The seas, and especially narrow sea passages, are critical to ensuring maritime transport and preventing possible threats. One such significant maritime passage is the Turkish Straits, formed by the Bosporus and Dardanelles Straits. The Turkish Straits constitute the sole connection from the Black Sea to the Mediterranean Sea, and so to the rest of the world. The significance is that whoever controls that choke point controls the passage of all ships between the two seas. In this case, control has been granted to Turkey by international agreement. ¹

This article revisits the Regime of the Straits, often known simply as the Montreux Convention (1936). ² It is an international agreement – signed by Australia, Bulgaria, France, Greece, Japan, Romania, Yugoslavia, the United Kingdom, the Soviet Union and Turkey – governing the Turkish Straits, and it is still in effect. It gives Turkey control over access to key straits of the Black Sea – an agreement that is considered a big win for the country's foreign policy to this day.

Section 1 of the Convention (Articles 2 to 7) relates to ‘Merchant Vessels’ and Section 2 (Articles 8 to 22) relates to ‘Vessels of War’. There is a Section 3 (Article 23) regarding ‘Aircraft on Vessels of War’. The purpose of the Convention today is not only the passage of ships, but also the security of Turkey and the other Black Sea countries (Bulgaria and Romania, who are members of the European Union and North Atlantic Treaty Organization (NATO), as well as Georgia, Moldova, Russia and Ukraine). ³

The regime it established is once again on the agenda following the military attack launched by Russia on Ukraine on 24 February 2022; the total blockade of Ukrainian ports by Russia between February and July 2022; the agreement brokered between the United Nations and Turkey to permit grain exports since July 2022; and the ongoing blockade of imports into Ukrainian ports. ⁴

Five issues are under discussion: (1) the dilemma of Turkey wanting to be neutral in the Ukraine war but being bound by the 1936 Convention; (2) whether Russian and Ukrainian warships will be allowed to pass through the Turkish Straits; (3) whether the future passage of warships from other states will be allowed in the event of possible international military measures against Russia; (4) whether warships from other states such as NATO could have established a naval humanitarian corridor between February and July 2022 to ensure the export of grain to prevent a global shortage due to the Russian blockade of Ukrainian ports; and (5) whether warships from other states such as NATO could be used to protect merchant vessels to enable imports to Ukrainian ports, given the ongoing Russian blockade.

This article examines these issues through six lenses: (1) the context of the current Russia–Ukraine conflict; (2) the Montreux Convention of 1936; (3) the geopolitical dimensions of the Montreux Convention of 1936; (4) the terms of the Montreux Convention of 1936; (5) adhering to the terms of the Montreux Convention of 1936; and (6) revisiting the terms of the Montreux Convention of 1936. The conclusions explore whether the Convention can survive this conflict, whether it needs to be renegotiated as naval warships and technology have changed dramatically since its signing, and, if renegotiated, whether this may well challenge other similar international agreements.

The context of the current Russia–Ukraine conflict

The Montreux Convention was aimed at providing some security assurances to Turkey and other countries on the Black Sea in the 1930s arising from the presence of foreign warships (the Convention uses the concept of ‘warship’ instead of ‘military ship’). The ongoing geographical aspect is that the Straits are the only sea passage between the Black Sea and Mediterranean Sea, and thus constitute a choke point. ⁵ Maritime choke points are located throughout indispensable marine trade routes and, in the case of global security problems, avoiding these choke points has often been suggested as a workable option. ⁶ However, as these Straits are the only sea passage between the two seas, going through them is the only viable option for any maritime trade with the states on the Black Sea.

A crisis has arisen with Russia implementing a full naval blockade of Ukraine's Black Sea ports between February and July 2022, and since then a blockade of imports to Ukraine. Russia has permitted exports of grain following a United Nations-brokered agreement. ⁷ At the onset of the conflict in February 2022, more than 100 foreign-flagged vessels and hundreds of mariners were stranded in Ukrainian ports. On 22 July 2022, the United Nations, the Russian Federation, Turkey and Ukraine agreed to the Black Sea Grain Initiative at a signing ceremony in Istanbul. ⁸

The Russian military strategy aimed to cut Ukraine off from its access to the Black Sea in order to decapitate its economy and, between February and July, threatened world food security. At the height of the export blockade, the Group of Seven industrial leaders expressed their anger at the situation at the World Economic Forum in Davos, Switzerland, in May 2022, ⁹ calling it the weaponization of food. ¹⁰ The export of Ukrainian grain provides food security for more than 300 million people around the world. The six-month blockade of exports left millions of tons of grain sitting in Ukrainian grain elevators or the cargo holds of the foreign ships stuck in Ukrainian ports, and much of this grain spoiled. ¹¹

The July deal allows the exports of grain, other foodstuffs and fertilizer – including ammonia – to resume through a safe maritime humanitarian corridor, but from only three Ukrainian ports: Chornomorsk, Odessa and Yuzhny/Pivdennyi. To implement the deal, a Joint Coordination Centre was established in Istanbul, comprising senior representatives from the Russian Federation, Turkey, Ukraine and the United Nations. According to procedures issued by the Joint Coordination Centre, vessels wishing to participate in the initiative will undergo inspection off the coast of Istanbul to ensure they are empty of cargo, after which they will be permitted to sail through the maritime humanitarian corridor to Ukrainian ports to load. Vessels on the return journey will be inspected again at the Istanbul inspection area. ¹²

This six-month blockade between February and July on the export of Ukrainian grain by the Russian Black Sea Fleet represented a serious global food security threat, and the ongoing blockade of imports, while aimed at preventing the flow of weapons, is further crippling the Ukrainian economy, causing suffering for its civilians. ¹³

The options open to the world are like those in all such global crises involving conflict: diplomacy and/or the use of military might to force an immediate solution. Further complicating the options is the Montreux Convention, which would prevent foreign navies from entering the Black Sea. There is no international police or international court that can be turned to. The United Nations can be a debating forum for such events and its members could vote to impose economic sanctions or embargoes. Individual states and others such as the European Union could also do so. However, history has shown that such measures take a long time to implement and they may not be effective, as there are those that will break them in illegal trade. ¹⁴

The situation was summed up by the United Nations Secretary-General, António Guterres, who pointed out that, while most attention is focused on the effects of the war on Ukrainians, it is also having a global impact, as the reduced supply of wheat and grain is increasing poverty and hunger, which could lead to increased social unrest. For example, the Arab Spring from 2011, with large-scale civil conflicts in Tunisia, Syria, Egypt, Libya and Yemen, was sparked by the high cost of food – and one Tunisian set himself on fire in protest. ¹⁵

Even though the export blockade has been broken by diplomatic means, the war has dramatically reduced grain production to less than a quarter of what it was. So, the Ukraine crisis still risks tipping up to 1.7 billion people worldwide – more than one-fifth of humanity – into poverty, destitution and hunger. ¹⁶

Prior to the conflict, Ukraine was one of the world's largest grain exporters and, in 2021, supplied around 45 million tons of grain to the global market. ¹⁷ Following Russia's attack on the country in late February 2022, mountains of grain built up in silos, with ships unable to secure safe passage to and from Ukrainian ports. Land routes were considered to neighbouring European Union countries, but no viable solution was found to transport the grain in the same volume that could be moved by ships. ¹⁸ Much of this harvested grain spoiled and became unusable. Given the war, yield decline is assumed for all scenarios since agricultural-technology applications will suffer due to a deficit of fuel, finances and manpower. It is projected that wheat production in Ukraine in 2022 will be 19.8 million tons. Thus, exports could be estimated at no more than 14–16 million tons, or a quarter of the production compared to 2021. ¹⁹

A brief issued by the United Nations Global Crisis Response Group on Food, Energy and Finance on 13 April 2022 called on international financial institutions to release funding for the most vulnerable countries, help governments in developing countries to invest in the poorest and most vulnerable by increasing social protection, and work towards reforming the global financial system so that inequalities are reduced. Two further briefs on 8 June 2022 and 12 August 2022 echoed this and analysed the deteriorating situation, as sufficient funding had not been forthcoming to answer this call. ²⁰

Even if sufficient funding had been forthcoming, there is no evidence that this would be more than a short-term measure to address the immediate symptoms caused by the war. Experts such as Trang Thi-Huyen Dinh, Duc Hong Vo, Anh The Vo and Thang Cong Nguyen note that the issues and problems, and their causes and solutions, addressed by the reports have been ongoing for years. The solutions they have voiced include stable governance and sustainable development. ²¹

Russia clearly is not aiming to cripple the world and has shown flexibility to address the global food problem it caused. The Russian Minister of Foreign Affairs, Sergey Lavrov, visited Turkey in June 2022 for intense negotiations on this issue of breaking the blockade and, while seemingly fruitless at the time, they nevertheless led to compromise by July to enable exports, but still preventing imports. ²² Only an end to the conflict will bring grain production back to its previous levels and end the global shortage.

While diplomatic efforts continue, the other alternative is military means. Since the end of the Second World War and the establishment of the United Nations, the use of military means for humanitarian purposes is normally preceded by a debate in the United Nations and the granting of a resolution. Those willing to implement the resolution have been a coalition as part of either a United Nations force or another regional organization such as the European Union or NATO. This is a significant point, as the Convention permits warships to pass through the Straits from the Mediterranean Sea into the Black Sea in the case of assistance rendered to a state that is the victim of aggression by virtue of a treaty of mutual assistance. This would bind Turkey, as concluded within the framework of the Charter of the United Nations. ²³

However, Russia, as a permanent member of the United Nations Security Council, would no doubt veto such a resolution, thereby bringing into question the validity of any NATO action. ²⁴ Furthermore, should any state proceed to break the naval blockade on humanitarian grounds, the act would clearly bring that state into direct conflict with Russia.

The presence of a western naval flotilla in nearby waters for the express purpose of countering Moscow's war strategy would no doubt be perceived as a military threat by Russia. That such a convoy would have an ultimate humanitarian objective will not negate Russia's perception. Thus, the cooperating states would need to balance the options and decide if they wish to enter the war on the side of Ukraine. Even short of Russia directly and deliberately attacking coalition ships, the risk of accidental escalation would be high, as demonstrated by the 1988 US downing of an Iranian civilian airliner (IR655) by the USS Vincennes while conducting a similar operation to protect oil shipments through the Arabian Gulf. ²⁵

In the face of these conditions, the contention that the United States and its allies can break Moscow's ongoing blockade of imports to Ukraine without firing a shot is dubious at best (or that they could have done so during the February to July export blockade). Here, neither the United States nor any other NATO member appears eager to challenge Turkey's implementation of the Convention. To illustrate, NATO warships have not transited through the Turkish Straits since the onset of the conflict in February 2022. ²⁶

The Montreux Convention of 1936

A mission that seeks to achieve humanitarian objectives through military means is still a military operation, carrying all the risks that this kind of action would normally entail. In addition, should any states proceed as a coalition of the willing to establish a humanitarian corridor or to break the ongoing naval blockade of imports (or had done so during the February to July export blockade) using their own naval vessels, then at the fore would be the need to adhere to the Montreux Convention of 1936, if they are to abide by international law and custom. Signed on 20 July 1936 at the Montreux Palace in Switzerland, the Convention went into effect on 9 November 1936, addressing the long-running Straits Question over who should control the strategically vital link between the Black Sea and the Mediterranean Sea. The agreement concerns the Dardanelles Strait, the Sea of Marmara and the Bosporus Strait. ²⁷

The Straits Question originated in the Treaty of Lausanne, a peace treaty negotiated during the Lausanne Conference of 1922–1923 and signed at the Palais de Rumine, Lausanne, Switzerland, on 24 July 1923. ²⁸ The Treaty officially settled the conflict that had originally existed between the Ottoman Empire and the Allied French Republic, British Empire, Kingdom of Italy, Empire of Japan, Kingdom of Greece and Kingdom of Romania since the onset of the First World War. The Treaty of Lausanne demilitarized the Dardanelles and opened the Straits to unrestricted civilian and military traffic, under the supervision of the International Straits Commission of the League of Nations.

By the mid 1930s, the strategic situation in the Mediterranean had altered, with the rise of fascist Italy. It controlled the Greek-inhabited Dodecanese Islands off the west coast of Turkey and had constructed fortifications on the islands of Rhodes, Leros and Kos. The Turks feared that Italy would seek to exploit access to the Straits to expand its power into Anatolia and the Black Sea region. There were also fears of Bulgarian rearmament. ²⁹ Turkey was not permitted to refortify the Straits. In April 1935, the Turkish government dispatched a lengthy diplomatic note to the signatories of the Treaty of Lausanne proposing a conference on the agreement of a new regime for the Straits, and requested that the League of Nations authorize the reconstruction of the Dardanelles forts. The Abyssinia Crisis of 1934–1935, the denunciation by Germany of the Treaty of Versailles, and international moves towards rearmament meant that the only guarantee intended to guard against the total insecurity of the Straits had just disappeared. ³⁰

In 1936, in response to Turkey's request to refortify the maritime area, the signatories of the Treaty of Lausanne and others met in Montreux, Switzerland, and reached an agreement to return the zone to Turkish military control. The Convention allowed Turkey to close the Straits to all warships in times of war and to permit merchant ships free passage. It remains in effect in 2023 and is thus relevant to the Russia–Ukraine conflict. The emphasis here is times of war. For the provisions of the Montreux Convention to go into effect, and especially for Turkey to start using its powers and responsibilities, a war situation must exist. According to international law, a formal declaration of war is not required for the definitive determination of a state of war. Even if there is no official declaration of war by the state using armed force, the laws of war should begin to apply when there is a substantial use of armed force. In the context of the Russia–Ukraine war, Russia officially declared that it had launched a special military operation against Ukraine on the morning of 24 February 2022 – an official declaration of the start of a comprehensive military operation against another state. ³¹

Historically, it should be noted from the outcome of negotiations agreed on in 1936 that the British, supported by France, sought to exclude the Soviet fleet from the Mediterranean Sea during the Second World War, where it might have threatened the vital shipping lanes to India, Egypt and the Far East. Britain's willingness to permit Turkey to have control has been attributed to a desire to avoid Turkey being driven to ally itself with, or fall under the influence of, Adolf Hitler or Benito Mussolini. ³² Turkey has used the Convention's powers before. During the Second World War, it closed the Straits to warships belonging to combatant nations. This prevented the Axis powers from sending their warships to attack the Soviet Union and blocked the Soviet navy from participating in combat in the Mediterranean. ³³

Now, the Montreux Convention is serving an important role in the Ukraine conflict. Ukraine asked Turkey to close the Straits to Russian warships, highlighting the Turkish role in keeping regional peace. The Turkish government agreed to this on 28 February 2022. However, several Russian warships have continued to enter and leave the Black Sea, with Turkey saying that it could not, and would not, prevent this if Russia claimed they were returning to their home port, as this is permitted in the Montreux Convention. ³⁴

Russia is taking advantage of this and, in essence, the freedom of movement enables its Black Sea Fleet to conduct business as usual. For example, these ships exit the Black Sea to perform tasks in the Sea of Japan – interacting with the Russian Baltic Fleet – and undertake regular patrols in the Mediterranean Sea. They then return to their home port in the Black Sea as and when they wish. At the time of the 2014 Crimean crisis, Russia's intent was to create a base on the Crimean Peninsula that would meet all the requirements for performing combat missions. ³⁵

The geopolitical dimensions of the Montreux Convention of 1936

There is a Turkish saying: ‘Did your ships sink in the Black Sea?’ The expression is used when a person is lost in thought, trying to resolve a seemingly unsolvable problem. As it turns out, this is the very body of water that has put Turkey on a geopolitical tightrope since Russia initiated its attack on Ukraine and began military operations from these waters. ³⁶

Located in the western part of the landmass of Eurasia, the Straits are conventionally considered the boundary between the continents of Europe and Asia, as well as the dividing line between European Turkey and Asian Turkey. ³⁷ The Straits – the Dardanelles and the Bosphorus – are two internationally significant waterways in north-western Turkey on opposite sides of the Sea of Marmara that create a series of passages that connect the Mediterranean Sea to the Black Sea. The Straits and the Sea of Marmara are part of the sovereign sea territory of Turkey and subject to the regime of internal waters, yet also subject to international agreements such as the Montreux Convention of 1936. ³⁸

The Dardanelles is a narrow strait in north-western Turkey, 61 kilometres long and 1.2 to 6.5 kilometres wide, linking the Aegean Sea (in the Mediterranean Sea) with the Sea of Marmara (in the Black Sea). ³⁹ The city of Dardanus in the Troad (territory around ancient Troy) was where Mithradates VI (King of Pontus) and Sulla (the Roman general) signed a treaty in 85 bce, giving the Strait its name. The location of the Dardanelles Strait has given it international political importance. ⁴⁰

The name Bosphorus is derived from the ancient Greek word bosporos, meaning ‘cattle strait’ or ‘ox ford’. The Strait is in north-western Turkey and separates Thrace from Anatolia. It is the narrowest strait in the world, with a length of 31 kilometres and a maximum width of 3.7 kilometres. The narrowest point is 700 metres wide, which is located between Anadoluhisari and Rumelihisari. Its depth ranges from 36.5 metres to 124 metres below the sea surface. It runs through Istanbul, the only city located on two continents. The Strait’s shore is heavily settled and part of the Istanbul metropolitan area, Turkey's largest metropolis with 17 million people. Two suspension bridges have been constructed across the Strait: the Bosphorus Bridge I (15th July Martyrs Bridge) was constructed in 1973, while the Bosphorus Bridge II (Fatih Sultan Mehmet Bridge) was completed in 1988. ⁴¹

Owing to their strategic importance in international commerce, politics and warfare, the sea straits connecting the Black Sea to the Mediterranean Sea have played a significant role in European and world history. A historical example of significance is when, in 1807 during the Napoleonic Wars, the British fleet under Sir John T. Duckworth closed the straits connecting the two seas and then forced them. ⁴² During the First World War, the Allies failed to capture this sea route, although a British submarine penetrated the minefields blocking the sea route and sank a Turkish battleship off the Golden Horn, an inlet on the Bosporus. ⁴³

The Straits are recognized as one of the seven maritime choke points in the world, which have gained immense ill fame in both past and present times, especially due to the heavy geopolitical pressure surrounding them. ⁴⁴ The Montreux Convention regulates maritime traffic through the Black Sea and guarantees complete freedom of passage for all civilian vessels in all circumstances in times of peace.

The terms of the Montreux Convention of 1936

The Convention consists of 29 Articles, four Annexes and one Protocol. Articles 2 through 7 consider the passage of merchant ships and Articles 8 through 22 consider the passage of war vessels. The key principle of freedom of passage and navigation is stated in Articles 1 and 2. Article 1 provides that the High Contracting Parties recognize and affirm the principle of freedom of passage and navigation by sea in the Straits, while Article 2 states that in times of peace, merchant vessels shall enjoy complete freedom of passage and navigation in the Straits, by day and by night, under any flag with any kind of cargo. ⁴⁵

In peacetime, military vessels are limited in number, tonnage and weaponry, with specific provisions governing their mode of entry and duration of stay. Warships must provide advance notification to the Turkish authorities, which, in turn, must inform the parties to the Convention. There is a formal process for ships, both military and non-military, in transiting the Straits. These are detailed in the Turkish Straits Maritime Traffic Order Regulations Enforcement Directives. ⁴⁶ There are also guidelines and recommended procedures by international organizations such as the Oil Companies International Marine Forum. ⁴⁷ The Turkish authorities observe the vessels as they transit the Straits, confirming that each ship matches the request for passage and the international registry of ships, while also confirming its weight – at least relative to the date of its construction.

Turkey is authorized to close the Straits to all foreign warships during a war or when it is threatened by aggression. Turkey is also authorized to refuse the transit of merchant ships belonging to countries at war with it. In wartime, with Turkey not involved in the conflict, warships of the nations at war may not pass through the Straits, except when returning to their base (Article 19). Articles 14 and 18 impose several highly specific restrictions on what types of warships are allowed passage. Non-Black Sea powers wishing to send a vessel must notify the Turkish authorities 15 days prior to the requested passing, while Black Sea states must submit their request eight days prior to passage. Furthermore, no more than nine foreign warships, with a total aggregate tonnage of 15,000 tons, may pass at any one time. Passage is also denied to single ships heavier than 10,000 tons. The aggregate tonnage of all non-Black Sea warships in the Black Sea must be no more than 45,000 tons, with no one state exceeding 30,000 tons at any given time. Non-Black Sea warships are not permitted to stay in the Black Sea for more than 21 days. Only Black Sea states may transit capital ships of any tonnage, to be escorted by no more than two destroyers. Any revisions to Articles 14 and 18 require a 75 per cent majority of the signatory countries and must include Turkey. ⁴⁸

Under Article 12, Black Sea states are allowed to send submarines through the Straits with prior notice if the vessels have been constructed, purchased or sent for repair outside the Black Sea. The less restrictive rules applicable to Black Sea states were agreed as effectively a concession to the Soviet Union, the only Black Sea state other than Turkey with any significant number of capital ships or submarines. ⁴⁹

The Convention contains no explicit prohibition on aircraft carriers. However, modern aircraft carriers are heavier than the 15,000-ton limit imposed on warships, which makes it impossible for non-Black Sea powers to transit modern aircraft carriers through the Straits.

Adhering to the terms of the Montreux Convention of 1936

While the Montreux Convention was designed for a particular geopolitical context in 1936, and remains unchanged since its adoption, it has endured as a solid example of a rules-based international order since most of the intent of its terms is still followed. ⁵⁰

To follow the intent of the terms, the former Soviet Union during the Cold War designated its Kiev-class and Kuznetsov-class ships as aircraft-carrying cruisers as the ships were armed with P-500 and P-700 cruise missiles, which also form the main armament of the Slava-class cruiser and the Kirov-class battlecruiser. The result was that the Soviet navy could send these aircraft-carrying cruisers through the Straits in compliance with the Convention, but, at the same time, the Convention denied access to NATO aircraft carriers, which exceeded the 15,000-ton limit. ⁵¹

Turkey chose to accept the designation of the Soviet aircraft-carrying cruisers as aircraft cruisers, as any revision of the Convention could leave Turkey with less control over the Straits, especially as another agreement, the United Nations Convention on the Law of the Sea (UNCLOS), had already established more liberal passage through other straits. Technically, UNCLOS governs transit passage through international straits around the world. However, Article 35 clarifies that UNCLOS does not apply to long-standing international conventions in force. ⁵²

By allowing the Soviet aircraft-carrying cruisers to transit the Straits, Turkey could leave the other elements of the more restrictive Montreux Convention in place. Today, there are no aircraft carriers, as defined by Russia, in the Black Sea Fleet. The upshot is that it is the Montreux Convention, and not UNCLOS, that governs the Turkish Straits, which enjoy a truly unique legal status in international transit governance.

Revisiting the terms of the Montreux Convention of 1936

The Convention remains in force, but not without dispute. It was repeatedly challenged by the Soviet Union during the Second World War and the Cold War. For example, for several years after the Second World War, the Soviets exploited the restriction on the number of warships by ensuring that one of theirs was always in the Straits, thus effectively blocking any state other than Turkey from sending warships through the Straits. ⁵³ Soviet pressure expanded into actual demands to revise the Montreux Convention, giving rise to the 1946 Turkish Straits crisis, which was one of the reasons that led Turkey to consider abandoning its policy of neutrality. In 1947, it became the recipient of US military and economic assistance under the Truman Doctrine of containment and, in 1952, it joined NATO, along with Greece. ⁵⁴ Although such growing Soviet threats to its security were a catalyst, Turkey saw its membership of NATO as both a security guarantee and a way of reinforcing its western identity. Seeking NATO membership was as much a political move as it was a military one. Turkey has implemented the Convention in full transparency and impartiality since then. ⁵⁵

The United States has not signed the Convention but generally abides by it under customary international law. In doing so, the Montreux Convention is an obstacle to US naval build-up in the Black Sea due to the Convention's stipulations regulating warship traffic by nations not sharing a Black Sea coastline. Those stipulations place Turkey's relationship with the United States and its obligations as a NATO member in potential dispute with Russia, and thus the regulations of the Montreux Convention. Russia may see an increased NATO presence in the Black Sea as escalation. ⁵⁶

UNCLOS, which entered into force in November 1994, may well prompt calls for the Montreux Convention to be revised and adapted to make it compatible with UNCLOS's regime governing straits used for international navigation. However, Turkey's long-standing refusal to sign UNCLOS has meant that the Montreux Convention remains in force without further amendments. Furthermore, disregarding the Convention and permitting NATO warships passage into the Black Sea would immediately escalate tensions between Russia and Turkey. Nevertheless, the Turkish Minister of Foreign Affairs, Mevlüt Çavuşoğlu, stood by its obligations to the Convention and announced on 27 February 2022 that his government would recognize the Russian attack as a war, and so implement Article 19 of the Convention with respect to vessels of war during a time of war. This meant denying passage to all military naval vessels, including those of NATO powers, which now cannot move their vessels from the Mediterranean Sea to the Black Sea. ⁵⁷

Çavuşoğlu further stated that, pursuant to the terms of the Convention, Turkey could not block Russian warships based in the Black Sea from returning to their registered base. Around 27–29 February 2022, Turkey denied three of four Russian warships permission to enter the Black Sea as they did not have a home base in the Black Sea. Russia had previously been deploying its Kilo-class submarines from the Black Sea to the Mediterranean for extensive periods of time, after which they would return to their home port in the Black Sea, thereby enjoying freedom of movement in both seas. At least six Russian warships and a submarine have crossed the Turkish Straits since the start of the Russia–Ukraine war in February 2022. ⁵⁸

Conclusions

Between February and July 2022, Russia maintained a total naval blockade of Ukrainian ports. Grain was not exported, threatening to leave hundreds of millions starving worldwide. The period was tense, questioning if other states, especially NATO members, would contravene the Montreux Convention and send naval warships to break the blockade and alleviate the global grain shortage.

Turkey and the United Nations brokered a deal with Russia to enable exports, but the same agreement also prevents any ships entering the Black Sea to import goods to Ukraine, as Russia is concerned that foreign weapons could be shipped there. Since July 2022, the terms of the Montreux Convention remain a focus of the humanitarian crisis as imports to Ukrainian ports are now blockaded by international agreement. Unless another agreement can be reached, foreign naval forces might need to enter the Black Sea and contravene the Convention. If this happens, it may open the door to challenging any other similar international conventions.

The agreement was for 120 days and, on 17 November 2022, Russia agreed to extend it for another 120 days under existing conditions without changes. In the weeks leading up to this, Russia repeatedly warned that it might not agree to extend the agreement because a separate deal, which was also signed in July, exempting Russian fertilizers from sanctions, had not been implemented. Russia also temporarily pulled out of the agreement at the end of October, accusing Ukraine of a massive drone attack on its Black Sea Fleet in Crimea. ⁵⁹

As the implementor of the Convention, the Turkish government finds itself in a difficult position. Article 19 of the Montreux Convention provides that if Turkey is not belligerent in a time of war, the warships of any warring state will be prohibited from passing through the Straits, except to return to their home bases. Herein lies a weakness, as it is possible to change a home port. Thus, while a home port of any ship (military or non-military) is defined when it is commissioned and enters service, this can change. The most common time to shift home port is in conjunction with major yard maintenance and docking availability. When the current conflict broke out, Turkey would have relied on information that had been provided by Russia and Ukraine prior to the onset of the conflict. There is no legal means for Turkey to challenge them should they inform Turkey during the conflict that more ships have been added to the list of ships with home ports in the Black Sea. At the same time, the warships of other countries that are sent to support Ukraine or Russia, or to break the Russian naval blockade of Ukrainian imports (or were sent to break the earlier blockade of exports as well), would similarly need to be banned, as these countries are regarded as warring countries and their home ports are not in the Black Sea. It would rest on Turkey to ban them.

Nevertheless, both Ukraine and Russia are important partners in critical energy and trade agreements for Turkey. Disregarding the Montreux Convention would immediately escalate tensions between Russia and Turkey. At the same time, Turkey, which has been a NATO member since 1952, wants to maintain or even strengthen its ties with the West. Its control over these key Straits may test its balancing act of relations with Russia and members of NATO and the European Union.

Furthermore, it is fair to say that the main things aggravating Turkey's difficult position are the very fundamental tenets of the international community – peace and stability. The justification for letting foreign naval ships into the Black Sea in contravention of the Montreux Convention would be based on humanitarian grounds. The need to end the conflict and restore grain production to its prewar levels remains a priority, even if exports are now permitted. With the war ongoing, the risk and potential remain that there will be no grain to export. Furthermore, as of October 2022, imports were still blockaded, and this has resulted in an ever-growing humanitarian crisis in Ukraine.

Foreign naval ships entering the Black Sea regardless of the reason would put the Montreux Convention of 1936 to the test, and it may not survive. A rationale for its renegotiation could be the fact that the Convention was signed 87 years ago, and naval warships and technology have changed dramatically since that time, thus making it difficult to apply the Convention's highly technical transit limitations to modern warships. Another reason is that the nature of just and unjust wars and what is permissible in war (jus ad bellum, which refers to the conditions under which states may resort to war or to the use of armed force in general, and jus in bello, which regulates the conduct of parties engaged in an armed conflict in legal terms) is no longer the same as it was between the two World Wars. So, other instruments, such as conventions, might also need to be amended to reflect this.

If this happens, it may well challenge similar international agreements or even the rationale of the way of life their implementation impacts. International agreements are formal understandings or commitments between two or more countries or international organizations that have been used for centuries to determine and regulate matters of concern to them and their relations in a normative manner. The bottom line, then, is that the international community must be sensitive to the effects of any potential naval responses to Russia, as they could implicate or even undermine the Montreux Convention, as well as other conventions. However, if diplomacy does not bring an end to the conflict, then this might be the only means.